Adding Public Documentation License v1.0

I'd like to 1) add this:
http://www.openoffice.org/licenses/PDL.html
as licenses/pdl-v1.0. It is rather similar to mpl-v1.0, but with a
documentation clause, as that is the focus of the license. It seems that it
can also be 2) default acceptable.
Please, approve/deny #1 and #2. aspell-ms needs this.